3.2.99-rc1 review patch. If anyone has any objections, please let me know.
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From: Lepton Wu ytht.net@gmail.com
This finally resolve crash if loaded under qemu + haxm. Haitao Shan pointed out that the reason of that crash is that NX bit get set for page tables. It seems we missed checking if _PAGE_NX is supported in kaiser_add_user_map
Link: https://www.spinics.net/lists/kernel/msg2689835.html
Reviewed-by: Guenter Roeck groeck@chromium.org Signed-off-by: Lepton Wu ytht.net@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org (backported from Greg K-H's 4.4 stable-queue) Signed-off-by: Juerg Haefliger juerg.haefliger@canonical.com Signed-off-by: Ben Hutchings ben@decadent.org.uk --- arch/x86/mm/kaiser.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/arch/x86/mm/kaiser.c +++ b/arch/x86/mm/kaiser.c @@ -189,6 +189,8 @@ static int kaiser_add_user_map(const voi * requires that not to be #defined to 0): so mask it off here. */ flags &= ~_PAGE_GLOBAL; + if (!(__supported_pte_mask & _PAGE_NX)) + flags &= ~_PAGE_NX;
if (flags & _PAGE_USER) BUG_ON(address < FIXADDR_START || end_addr >= FIXADDR_TOP);